High-frequency control of alpha kerr cell



355 much higher than this lo Patented Apr. 28, 1931 r.;

tm-ED STM-Eg" Letizia f'rnEononn wIInAnn oAsn, or AUBURN, YORK, AssiGNoR ro Riisniireont,l

LABORATORY, iNcoRronArnn, OF AUBURN, Nnw YORK, A CORPORATION or Nnw YORK l V 4Application nieu July 23,

- This invention' relates to certain new and useful improvements in high frequencycontrol of a cell capable of showing the Kerr effect and has many applications as for injg" stance the production of a photographic record of light waves corresponding to sound wave variations, television, etc.

-A primary object of the invention resides inthe production of an eii'ective apparatus 1b: embodying a high frequency carrier `c urrent modulated in any suitable wayin accordance with the results desired and adapted to energi'ze a cell capable of showing the Kerr effect. in such a manner as to vary a beammipolar; ized light in accordance with the modulations impressed on the carrier current for the production, as an instance, of a photographic record of light waves corresponding to sound 4Waves. .-.s -if f f2 Other objects and advantages relate to the details of the structure and the form, arrangement and relation of the parts thereof, all as will more fully appear from the fol-- lowing description talren in connection with y 255 the accompanying drawing, in which .-The ligure is a diagrammatic illustration of an embodiment ofthe invention.

-For controllingl the action of a cellcapa-i ble of showing the Kerr effect, it is found del sirable to utilize a modulated high frequency voltage of a frequency higher than the most rapid variations of the modulating wave so as not to cause mutual interference. -'f 'i -The value of this frequency may be as er limit as may be i deSirab1e -.1g nffv'il L M fr 1.,

VWhen it is desired to utilize the invention to control the light transmission through the cell in accordance with a sound wave-source, I-utilize circuits corresponding quite closely to those employed in high quality radio tele-f phone transmitting stations. 1- lil V The drawing illustrates a circuit employ-- ing the constant current system -of modula-V It5''tion, but I do not wishto'helimited to any single system of high frequency current generation and modulation, as many other sys tems accomplishing the same results by otherL means are known and equally applicable to` this invention. f'

i HIGH-FREQUENCY CONTROL or A Nunn cm1. i'

1928;. serial No. 294,868. -As specically'illustrated inthe drawing, sound waves are impressed upon asuitable microphone -lwhich is connected in series with a battery -2- and the primary Winding of the transformer This induces a potential inV4 the seconda-ry coil of transformerl 3- which in turn varies'the potential of' the grid 5- with respect to. the iilament -6-.. Battery 1 supplies asuitable biasingpotential. Battery -9- eo` serves to'heat the lilament 6- and battery- -lO- supplies'the potential for. the plate; circuit of the electron tube-S- aslwellY asfor the-plate circuit ofelectron tube--24-- Voltage variations impressed on thegrid o5 -5- cause corresponding fluctuations in` the current iiowing between. the plate -7- andiilament un. 1

These current fluctuations cause voltage fluctuations across the-terminals of coil l1-"- which is wound so that its inductance is' very high. 5""1' `,1 'Coil -ll-` is cornriiorrto the plate circuits of both electron tubes 8-and -2=l-, hence voltage variations produced' by fluctuations 75 of'current'flowing between'n and #T- will cause effective voltage variations inthe' plate circuit of tube -QLl- An oscillatoryy circuit vconsisting of coil -14-1- and condenser 15- i'sco'nnected bet-Ween the S0' grid -2land the filament -22- of the tube 244. "'Battery -'16'-' supplies asuitable biasingpotential for'tlie'grid'f-ZIM.` Coil -17- is coupled magnetically with coil 14- and wound in` such a direction as to. 85'

produce self-oscillation in the tube -24. 7 'Il Condenser 13- serves as a low impedance vby-pass for the high frequency currentl around the coil -1l`-. Coil .-12-9, a high frequency. choke, tends to-keep the high frequency current outof the-plate circuit of' tube 8ff g;

The amplitude of thecurrent lgenerated coils 1414-. andv1 -vl7--,,.WillI depend touaaz 95; considerable extent upon the effective volt-- age in the plate circuit of tube-Z-e This' effective plate vOltagewwill-bethes sum ofthe potential of the battery --10- and whatever voltage may be induced in coil `-11asfthe` 100 result of the fluctuations in the plate current of tube -S-.

Due to the magnetic coupling between coil 1S- and coils -14- and l7, fluctu- 5 ating high frequency voltages and currents Due to diii'erences in the electrical-charac;

teristics of various types of cells showing that. Kerr effect, I may choose to apply the high frequency voltages induced in the coil -18 directly to the terminals of the cell Q5- by A-Vith certain types of cellI mayprefer to. 2m partially or completely rectifyl the. voltages induced in coil -lS- beforel applying them to the cell In this event a suitable rectifier' would be associated with the output coil 1S- and for this service a hot cathode 25 Vacuum tube rectifier has been found particularlysuitable` A possible application is i1- lustrated in the drawing on which---land --82- respectively represent. the filament and plate of the hot cathode rectifier 3. Battery -36 or its equivalent supplies current to the filament S- to maintain it at the requisite temperature. Condenser -31- acts as a shunt across the-leads to the cell and is used whendesirable.

35 In accordance with the known operation of a cell capable of showing the Kerr effect, the Voltage'induced in coil l8 willcontrol the light passing from source -30 through the crossed Nicol prisms -,28 -and -9.9, 4o: or their equivalent.

The arrangement 'here illustrated inthatJ connection. comprises. a straight line source of light such as an electriclamp 3Q- having a straight line filament extending parallel with the opening between the electrodes -26- and -27. The light from this source passes through the Nicol polarizer -2lv and. is focussed. by a lens or lenssystem -40- on the space between the electrodes -26- and ,-.-s'i'. The light emanating from the space between the electrodes then passes through the Nicol analyzer -29- and preferably through a lens or lenssystem -41- which focusses the light upon e the photographic film -'l2, an opaque barrier i3- being provided in front ofthe film and having an extremely narrow elongated slit through which the light passes to the film." Other'lneansn may, however, be

` relied upon for focussing a line of light of desired size uponthe film or sensitized surface. i i v y with coil -18- to-tune the-combination to 95:. resonance, and hence produce a maximum effeet at the frequency of oscillation of the tube -2-.l. In some cases it is found that resonance tuning in coil 1S- is not essential, and in such-cases condenser 19- may be omitted and in some cases the natural or inhei-ent capacitance of the 1coil-,I Sf'may be sufficient' to tune it`- to resonancewithout the use. ofsthe condenser -l9.

. When the inventan isto be operated from. other than a soiuid control source, as specifi- 75 cally illustrated in the drawing, as fo'r'instance when used in television` tele-photography and the like, for which uses it is well adapted,.the circuit. shown. in the drawing need only be modified to allow the application of thel necessarycontrol-.voltages ampliiiedto the proper degree by external.' amplifiers; be` x tween grid and the'lilament 6l-#off the electron tube -8-, s

Then the operation-of thecellis to. beiconf- 55 trolled buv-.radio or carrier current signals, as i for instance. in the recordingof telephone signals, and in telephotcgraph-y oi' ltelevision transmitted by-radio Aor carrier current, Athe modulated oscillator wilt be-locatedr'in the 90; transmitting; equipment and the modulated high frequency voltages received-from the antenna orinconiing lines may be-applied d-g rectlyto-the coil '-18-after having been amplified up to the proper level .by :inysuit- 95. able amplifier system.` g z Altho I have shown-and described a specii'ic apparatus as constituting an embodiment of the invention I do not desire to restrict myself to the details of formconstruction, ar- 10Q rangement or. association of the parts there, of, as various changes and-modifications may be made wit-hin. the. scope of the :appended claims. Iclaim: 'v'

t., .105 il; vIn an apparatus of=the=class described, an electrical circuit including local means for. producing a high frequency oscillating current, means for modulating said-current in, accordance with sound wave. Variations, 110 means for rectifying said current, and a cell, capable of showing the Kerr effect electrical-i ly associatedwith said circuit-=.; vm.; a

apparatus of the class described, an electrical circuit including local means for 115. producing a high frequency oscillating-current, meansfor modulating said current in accordance with sound wave variations, means for rectifying said current, a cell capable of showingthelerr effect electrically associated. with said circuit, means for causing polarized: light to pass through said cell, and means orproducing a 4Visible `record of light rays as -varied by said cel.l.. fief-1;@ ;.'.j..,,yr. .:iz g1 l 3.. In an apparatus ofthe class described, an.. 125. electrical circuit including local means for producing high frequency oscillating currentz means formodulating said circuit .in accord ance with. sound wave variatiens,. means for rectifying said current, a cell capable of show- 13a ing the Kerr effect and comprising a pair of spaced electrodes connected in said circuit, means for causing polarized light to pass through said cell and means for producing a 5 photographic record of light rays as varied by said cell. 4. In an apparatus of the class described, e an electrical circuit including local means for producing high frequency oscillating current, means for modulating said current in accordg ance with sound wave variations, means for rectii'ying said current, a cell capable of showing the Kerr etfect and comprising a pair of spaced electrodes connected in said circuit, means for causing polarized light to pass through said cell and means for producing a visible record of light rays, as varied by said cell.

In an apparatus of the class described, an electrical circuit including local means for producing a high frequency oscillating current, means for modulating said current in accordance with sound wave Variations, means for rectifying said current, a cell capable of showing the Kerr eect and including an envelope having closely spaced electrodes therein, and means for conducting said rectified current to the electrodes of said cell.

6. In an apparatus of the class described, 3o an electrical circuit including means for producing locally a high frequency oscillating current, means for modulating said current by electrical variations locally applied, means for rectifying said current, a cell capable of 35 showing Kerr effect including closely spaced electrodes, and means for conducting said rectifying current to the electrodes of said cell.

In witness whereof I have hereunto set my 4o hand this 20th day of July, 1928.

THEODORE WILLARD CASE.

i i, i 

